Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 464056 | Metric tons | NA |
| 2004 | 564015 | Metric tons | 21.54 % |
| 2005 | 425630 | Metric tons | -24.54 % |
| 2006 | 435273 | Metric tons | 2.27 % |
| 2007 | 613895 | Metric tons | 41.04 % |
| 2008 | 374933 | Metric tons | -38.93 % |
| 2009 | 511429 | Metric tons | 36.41 % |
